Electrophotographic imaging processes and techniques have been extensively described in the prior art. Generally, such processes have in common the step of imagewise exposing a photoconductive element to electromagnetic radiation to which the element is sensitive, thereby forming a latent electrostatic charge image. A variety of subsequent operations, well known in the art, are then employed to produce a permanent record of the image.
Daniel et al in U.S. Pat. No. 3,567,439 discloses cyanine and styryl dyes containing 1,3,2-dioxaborinium salt moieties which are useful as spectral sensitizers for organic photoconductors of the triarylmethane type.
Halm in U.S. Pat. No. 4,123,268 describes similar boron diketonate chelates which lack the methine group of the cyanine and styryl dyes cited above. These boron diketonate chelates when blended with certain polyvinylcarbazole polymers or with triphenylamine produce photoconductive coatings of high electrophotographic sensitivity in the ultraviolet region of the spectrum.
The boron diketonate-sensitized photoconductive compositions described by Halm are severely range-limited in spectral response. The cyanine and styryl boron dyes described by Daniel et al show a broad spectral response but are not as effective in increasing the quantum efficiency of photoconductive compositions.